A DC to DC converter may be used in a variety of electronic devices to convert an input DC voltage to an output DC voltage. One DC to DC converter may have a transformer based full bridge primary and a current doubler rectifier secondary topology. In this instance, a full bridge circuit may be coupled across a primary winding of an isolation transformer and a current doubler rectifier circuit may be coupled across a secondary winding of the isolation transformer. The full bridge circuit may have four switches arranged in known bridge configuration. The current doubler rectifier may have two switches.
In one known arrangement, the four switches of the full bridge circuit may be controlled by four separate control signals and the two switches of the current doubler rectifier circuit may be controlled by an additional two control signals. Thus, six different control signals are required in this known arrangement. In addition, six switches may be responsive to these six associated control signals such that before each power transfer cycle, the secondary winding is shorted, but the primary winding is left open (the four switches of the full bridge are open). This known arrangement therefore requires a relatively larger core size for the transformer since for each cycle on the magnetization curve, the core will almost be brought back to the initial state where the core is not magnetized.
A DC to DC converter may have multiple transformer based power units. In one embodiment in the prior art, a controller for such a DC to DC converter may be a current-mode controller providing out of phase pulse width modulated signals to each power unit. Current sensing information for each power unit may be fed back to the controller. Separate current channel paths for each power unit may have many separate components contributing to mismatches between the different current channels for each power unit, e.g., mismatch can be +/−30% or even higher. This can degrade the efficiency and reliability of such DC to DC converters.
Although the following Detailed Description will proceed with reference being made to illustrative embodiments, many alternatives, modifications, and variations thereof will be apparent to those skilled in the art. Accordingly, it is intended that the claimed subject matter be viewed broadly.